diff --git a/GodotHelper/src/Math/Planes.cs b/GodotHelper/src/Math/Planes.cs
new file mode 100644
index 0000000..7121ef7
--- /dev/null
+++ b/GodotHelper/src/Math/Planes.cs
@@ -0,0 +1,14 @@
+namespace GodotHelpers;
+
+using Godot;
+public static partial class SJKMath
+{
+  public static Vector3? MouseToPlane(this Plane plane, Camera3D viewCamera, Vector2? mousePos = null)
+  {
+    var from = viewCamera.ProjectRayOrigin( mousePos ?? viewCamera.GetViewport().GetMousePosition());
+    var normal = viewCamera.ProjectRayNormal(mousePos ?? viewCamera.GetViewport().GetMousePosition());
+    return plane.IntersectsRay(from, normal);
+  }
+  public static Vector3? MouseToGroundPlane(this Camera3D viewCamera, Vector2? mousePos = null, float offset = 0) =>
+    (Plane.PlaneXZ with { D = offset }).MouseToPlane(viewCamera, mousePos);
+}